Layout Algorithm Dialog Window

This dialog window can be used for controlling the graph layout algorithm (automatic layout) and interactive fine tuning operations (manual layout).

In daVinci V2.x, fine tuning is available to move a node vertically to another level by keeping the graph visualization hierarchically. Read more about graph layout and hierarchical visualizations in the concept document. By default, the layout algorithm keeps the nodes at their current levels when a new layout is calculated. This behaviour can be switched off by deselecting check button Keep Nodes at Levels. In this case, nodes are always assigned back to their initial level when the layout algorithm is started again with menu Layout/Improve All.

The Quality slider is used to adjust the accuracy of the layout algorithm, i.e. the number of iterations of the Sugiyama graph layout algorithm. The higher the slider value, the better the layout results which will give a reduced number of edge crossings. But higher settings need a lot of computing time, especially for very large graphs..

For the fine tuning (manual layout), some Constraints can be set to control horizontal movement of a node. The three constraints specify the behaviour when a node, moved with the mouse, will touch its left or right neighbour node at the same level. A neighbour node is touched when the minimal node distance is reached by the mouse pointer.

• In default mode Preserve Node Order, the touched node is moved as well to keep the order of nodes.

• In mode Modify Node Order, the moved node and the touched node exchange their position as soon as there is enough space to do so. This mode is useful to modify the order of nodes on a level, e.g. to remove edge crossings by hand.

• In the third mode Fixed Neighbour Nodes, fine tuning stops as soon as a neighbour node is touched which is useful to protect the position of neighbour nodes.

Dialog Items of the Layout Algorithm Window

• Keep Nodes at Levels
  Keeping the graph nodes at their current level when a new graph layout is calculated by starting the layout algorithm with menu Layout/Improve All. Nodes may be assigned to a new level by using vertical fine tuning. If you want to set the nodes back at their initial levels with the next run of the layout algorithm, then deselect this check button.

• Quality
  Setting the accuracy of the layout algorithm to some abstract value between 1 and 5. The higher the slider value, the better the layout results (reduced number of edge crossings). But higher settings need a lot of computing time, especially for very large graphs.

• Preserve Node Order
  Fine tuning constraint for horizontal node movement to keep the order of nodes at a level.

• Modify Node Order
  Fine tuning constraint for horizontal node movement to exchange the order of nodes at a level.

• Fixed Neighbour Nodes
  Fine tuning constraint for horizontal node movement to freeze the position of all other nodes at a level.

• Apply
  Push button to accept the current settings of this dialog window. Without pressing Apply, modifications to these options are not considered by daVinci.

• Cancel
  Push button to close the layout algorithm dialog without performing any action.

• Reset
  Push button to undo any modification to these options unless Apply is not pressed. So Reset goes back to the current settings.

• Help
  Push button to start the online help system with this page.